late 14c., from un- (1) "not" + past participle of wash (v.). Replaced Middle English unwashen, from Old English unwæscen. Noun sense of "the lower class" is attested from 1830.
the unwashed masses
a sink full of unwashed dishes
unvarying
unveil
unwanted
unwarranted
unwary
unwashed
unwavering
unwearied
unwed
unwelcome
unwell